Compound hydraulic machine



0 United States Patent 1111 3,548,715

[72] Inventor Gerhard Bobs! [56] References Cited w. Switzerland UNITEDSTATES PATENTS P 1,083,329 1/1914 Lancia.... 103/126 [221 med d 19701,870,192 8/1932 Butler..... 103/126 [453 v AG 1,927,395 9/1933 Edwards.103/126 Asslgn g and 2,212,994 8/1940 Vrolix 103/126 3 2,218,406 10/1940Orshansky. 103/162 2,312,417 3/1943 Jones 103/162 [321 Pmmy 1 2,817,95312/1957 13 11111.. 103/162 [331 f'gs 2,936,716 5/1960 Looker 103/113,065,700 11/1962 Blelke 103/162 FOREIGN PATENTS 1,261,092 4/1961 France103/162 Primary Examiner-William L. Freeh 541 COMPOUND HYDRAULIC MACHINEY- & Fflshauf 6 Claims, 5 Drawing Figs. [52] US." l/6 ABSTRACT: Anauxiliary low-pressure pump unit is con- 4 /206 (DiScl0S r L4l7/244:9l/49Q 311g nected to a high-pressure pump, or hydraulic motor unit to417/ 9? prevent cavitation effects at high speed; the auxiliary unit isa [51] Int. Cl. .,F04b 23/08, gear pump, both pump units are located inthe same housing F04b 23/ l 2, F04b U07 and one of the gears of the gearpump is directly mounted on a [50] Field of Search l03/l02; rotatingelement of the high-pressure unit, for example on a rotating cylinder orother rotating element thereof.

PATENTEU 05622 I970 3.548 715 SHEETl or 2 Fig.1

16 I5 I4 /7 I312 27 28 INVENTOR GEZIIWBD 30557 BY We 14 ATTORNEYPATENTEU [15222 I976 SHEET 2 OF 2 COMPOUND HYDRAULIC MACHINE The presentinvention relates to hydraulic machines, which, for purposes of thisapplication, are defined as hydraulic apparatus which can act both as apump or as a hydraulic motor unit. In particular, the application isdirected to hydraulic machines having a cylinder and piston assembly, inwhich a plurality of cylinder bores are located around an axial shaft,and the pistons are slidable therein and connected to a wobble plate. Alow-pressure gear pump is in driving connection with the high-pressurehydraulic machine unit, so that a compound machine is obtained.

Rotary hydraulic machines, and in particular rotary hydraulic pumps ofthe multiple parallel piston type are frequently operated at-such speedsthat the hydraulic fluid can no longer be completely sucked into thecylinders at the low-pressure side of the pump, to completely fill thecylinder. Additionally, upon interruption of flow, the well-knownunder-pressure effects and noise due to cavitation will result. Pumps ofthis type are usually, therefore, supplied with fluid at an initialpressure of a few atmospheres at their low pressure side. The pressurefor this low-pressure supply is usually obtained by means of gear pumpsor similar displacement pumps, combined in a suitable manner with thehydraulic apparatus. Usually, such an auxiliary pump, also referred toas a supply, or feed pump, is located outside of the housing of the mainpump and secured thereto. Occasionally, the feed pump will be entirelyseparate of the hydraulic machine. The drive'to the feed pump is usuallyon the same power shaft as that of the main or highpressure hydraulicmachine (operating either as a pump, or as a motor). It may be drivendirectly from the same shaft, or from a branch drive connected to thepower shaft. Such additional drive arrangements require additionalmaterial and adjustment costs, thus making the entire unit moreexpensive.

It is an object of the present invention invention to provide anintegrated compound unit not requiring specifically ar ranged separatedrive elements for an auxiliary, or feed pump in connection with ahydraulic machine.

Subject matter of the present invention: Briefly, the auxiliarylow-pressure unit is a gear pump, having at least one gear directlymounted, internally of the high-pressure machine, on a rotating elementof the high-pressure unit, for example on a rotating element of themachine unit itself, or on the drive shaft therefor; both the gear pumpunit and the high-pressure unit are located in the same housing to avoidadditional special fluid conduit connections.

Embodiments of the invention will be described by way of example withreference to the accompanying drawings, wherein:

FIG. 1 is a longitudinal cross-sectional view through a compoundhydraulic machine in accordance with the present invention;

FIG. 2 is a cross-sectional view at right angles to FIG. 1;

FIG. 3 is a longitudinal sectional view of a different embodiment;

FIG. 4 is a partial cross-sectional view, at right angles to the view ofFIG. 3; and

FIG. 4a is a partial cross-sectional view of an auxiliary pump bodyusing a hollowshaft to serve, simultaneously, as a duct and attachmentof the body.

Referring now to the drawings, and more particularly to FIGS. 1 and 2: Apair of wobble plate type hydraulic machine units 1, 2, are located in ahousing adjacent each other. The housing has a bottom part 3, an endplate 4 and a cover plate 5. Each one of the hydraulic machines 1, 2,which may operate as pumps or as hydraulic motors, are provided with ashaft 6, supported in the front portion of housing unit 3 in a rollerbearing 7, and in the end plate 4 of the housing in sleeve bearing 8.The bore 9 in the front of housing 3 is closed off by means of a cover10, supplied with the usual elastic seals to close off the shaft 6 fromthe interior of the housing. Such seals are not shown nor furtherdescribed in detail since they are well known in the art.

Each one of the hydraulic machines, themselves, includes a control plate11, having notches or grooves therein which communicate with controlbores 12 of a rotating cylinder 13. Cylinder 13 has a group of parallel,axially extending bores arranged therein, circumferential around shaft 6(as best seen in FIG. 2) in which pistons 14 are slidable. The pistons14 engage, by means of a ball joint and glide track 15 a wobble plate16. The track 15, or the entire wobble plate l 6 is inclined withrespect to the axis of the shaft so that the pistons, upon rotation ofthe cylinder, will move back and forth in the cylinder bores.

Each of the two cylinders has a gear 17, 18,-secured thereto, the gearsof the two cylinders being in meshing engagement. Gears i7, 18 arepartly closed off by a pump body unit 19, located within the housing ofthe compound machine. As best seen in FIG. 1, housing 19 may either by asingle unitary element or consist of a central part 20 and sidewalls 21,22

secured together by screws-23. Body 19 is so made that one sectionthereof just covers the teeth of gears 17, 18, and a portion of thesidewalls 21,22 closes off the gears at their side faces (see FIG. 1). Aspace 24 is formed by the gears 17, 18 and housing 19, to which a duct25 is connected which terminates in a duct formed in the end plate 4..

The two gears 17, 18 must be exactly aligned, and at least one of thehydraulic machine units therefore is preferably axially adjustable orthe location of cover plate 10 is so arranged that the two gears meshexactly and are in exact side alignment.

Body 19 itself is secured within the housing of the compound hydraulicmachine by means of a bolt 26, and is slidable axially (that is, in FIG.1 left and right) thereon for self-alignment with the gears.

In an alternative construction, bolt 26 may be replaced by a hollowbolt, and a connection formed from chamber 24 to the interior of thehollow bolt. in this case, the hollow bolt will supply, or conduct offfluid similar to duct 25.

FIG. 4a illustrates the alternative construction, wherein a hollow bolt56, having a slit formed therein, communicates by means of a channel 55with chamber 24. The other end of the bolt 56 may likewise be slit, orcommunicate directly with a duct in end plate 4 through the axialopening.

Gears l7 and l8,and body unit. 19 together form a gear pump. When thehousing is filled with hydraulic fluid, the two hydraulic machines willrotate in the-direction of arrows 27, 28 (FIG. 2) and fluid will beconducted into the space formed by chamber 24, and from then on throughduct 25 in the end plate 4. From end plate 4 the fluid, undersomepressure, can

be conducted to any utilization connection, or the end plate 4 mayitself serve for interconnecting channels formed or cut therein tosupply the various cylinders in the hydraulic machines.

If both gears are secured to the outside of the cylinders, then only oneof the shafts 6 need operate as a power shaft, that is to supplypowerto, or take power from the hydraulic machines. Gears 17, 18, thentransfer power to the hydraulic machine unit which is not driven (ordoes not supply rotary power to a utilization device), so that gears l7,18 will have a dual function of drive and hydraulic pump.

If the hydraulic machine units rotate in directions opposite to arrows27, 28, then the interior of the housing itself will become the pressureunit for the feed pump, and the space 24 the supply, or inlet duct. Inthis case, the housing, and its seals must be so formed that theresulting pressure will not cause leaks.

The two units of the hydraulic machines may form a hydraulic drive, inwhich the speed of the unit operating as a pump may be different fromthe speed of the unit operating as a hydraulic motor. Thus, the twogears 17, 18 may no longer be fixed to the cylinder units and restrainedfrom relative rotation with respect thereto. If, for example, gear 18surrounds the cylinder unit which operates as a hydraulic motor, thengear 18 will be fixed over cylinder unit 13 so as to be rotatabletherewith. When the pump unit, that is the unit with gear 17, is drivenat a given speed, the gear 17 will drive gear 18 with the speeddetermined by the ratio of the gears themselves. The speed of thehydraulic motor, however, will depend on the volume of hydraulic fluidsupplied by the unit forming the pump and, if the volume of supply ischangeable (for example by changing the inclination of the slide track15 or the wobble plate 16), then the speed of the motor may itselfchange correspondingly, for example between zero and a maximum valuedepending on design. The absolute speed between gear 18 and the cylinderelement of the unit functioning as a hydraulic motor will then be thedifference or, respectively, the sum (depending on direction ofrotation) of the speed of the gear 18 as determined by the driving speedof the pump unit and the speed of the hydraulic unit functioning as amotor.

In the construction of H65. 1 and 2, the cylinder unit is driven, thewobble plate remaining stationary. FIGS. 3 and 4 illustrate aconstruction in which the cylinder unit is arranged with its centralaxis at an inclination with respect to the power shaft, with powerdriven pistons. The housing is formed of a central portion 31, a frontcover 29 and a rear cover 30. Power shaft 32 is rotatably journaled infront cover 29 and further in an intermediate wall 33 located in centralhousing part 31. A drive disc 34 has pistons 36 connected thereto bypiston rods 35, terminating in wall joints (not specially shown and wellknown). The rotating cylinder 37 is journaled in a swingable retainer 38formed with the fluid supply grooves therein, cooperating with the boresof the cylinder unit 37. The ducts, the arrangement of which is alsoknown in the art, are located coaxial with retaining unit 38, connectionto the supply ducts (not shown) being over the duct 39 shown in brokenlines.

The portion of the drive shaft 32 lying between walls 29 and 33 isutilized for the auxiliary or feed pump. Gear 40 is secured, in drivingengagement, to shaft 32, to rotate therewith, and to mesh with a secondgear 41, journaled within gear body 42. Gear body 42 (FIG. 4) comprisesa central portion 43, as well as a pair of sidewalls 44, 45, snuglysurrounding the faces of gears 40, 41. Body 42 is secured between walls29 and 33 by a bolt 46, to be axially movable for self-alignment. Gears4t), 41 together with body 42 form a space or chamber 47 (FIG. 4) towhich a hydraulic line 48 is connected. Space 47 forms the pressurechamber of the gear pump formed by gears 40, 41 and body 42, when thegears rotate in the direction of the arrows 49, 50. Fluid under pressureis conducted over line 48 to the high-speed, high-pressure mainhydraulic unit, or provides an additional, low-pressure removal ofhydraulic fluid when the main unit is operating as a motor.

Various modifications may be made in the compound hydraulic machine ofthe present invention. For example, the unit as illustrated in FIGS. 1and 2 can be so arranged that an intermediate gear is located betweentwo adjacent hydraulic machine units. This will then result in a gearpump having three gear elements. A pair of gear pump bodies 19 must thenbe used, each one forming with a pair of gears a respective pressure andsuction region. A pair of connecting conduits 25 must then also be used,which, for example, may be joined together in the bottom plate 4 of thehousing. More than one additional intermediate gear can, of course, beused, each one pair of gears being furnished with its own housing toform a pressure and fluid supply region.

if individual high-pressure hydraulic machine units, located adjacenteach other, are to be individually driven, then the gear rings of one ofthe units must be rotatable with respect thereto in order to enableindividual drive of the separate hydraulic machine units.

Use of the hydraulic machine, in accordance with the present invention,as a pump causes reactions to the housing 19 (or, 42, respectively) dueto the pressure of the hydraulic fluid and due to the torque of thegears themselves. Such reactive forces can readily be absorbedbyimechanical reinforcements and hydraulic seals.

The present invention has been described with specific reference torotary axially extending wobble plate type piston pumps, designed forhigh-speed operation; various changes and modifications may be madewithin the inventive concept to accommodate design requirements.

lclaim:

1. Compound hydraulic machine comprlsingan enclosed housing; v

at least a pair of rotary cylinder-wobble plate-type highpressure pumpelements 13, 14, 15, 16 located within said housing; I

a gear 17 directly mounted on the outside circumference of the cylinder13 of at least one of said pump elements;

a second gear 18 located within saidenclosed housing and in meshingengagement with said first gear 17;

a pump body 19; 20, 21, 22, 23 located within said enclosed pump housingand at least partly enclosing the gear 17 secured to said cylinder 13 ofat least one of the pump elements, and said second gear, said pump bodyoverlapping the side faces of said gears, at least in part;

duct means 25, 24 connected to said gear body 19 conducting fluid pumpedfrom the space within the enclosed housing, under pressure, uponrotation of said cylinder and thus said gears; and

a power shaft 6 passing through said housing transmitting power to, orfrom said machine and connected to at least one of said pump elements.

2. Hydraulic machine according to claim 1, wherein said machinecomprises at least two high-pressure units having their central axeslocated parallel to each other, one of said units, only, having anelement in direct driving engagement with said shaft, each said unitshaving a gear mounted on a corresponding element, said gears forming thegears of said gear pump and simultaneously providing for transfer ofrotary power.

3. Hydraulic machine according to claim 2, wherein the gear on the unitnot directly connected to said power shaft is rotatable with respect tothe element on which it is mounted, whereby said element and said gearmay operate at different speeds.

4. Hydraulic machine according to claim 1, wherein said machinecomprises at least two high-pressure units located adjacent each otherand having their central axes parallel to each other; the outside ofeach cylinder assembly element being formed with a gear ring meshing agear ring of an adjacent unit, said gear rings forming the gears of saidgear pump and simultaneously providing for transfer of rotary powerbetween said units.

5. Hydraulic machine according to claim 1 wherein said pump bodyseparates the suction side from-the pressure side of the gear pumpformed by said meshing gears, said pump body being supported within thehousing and being axially moveable with respect to said cylindercarrying said gear, to provide for self-alignment of said pump body withrespect to the rotary cylinder of the high-pressure pump element.

6. Hydraulic machine according to claim 1 wherein said pump bodyseparates the suction side from the pressure side of the gear pumpformed by said meshing gears, said pump body being formed with adifferential pressure chamber 24; a hollow shaft 56 supporting said pumpwithin said housing, the interior of said 56 shaft being in fluidcommunication 57,56 with said chamber 24 whereby said shaft willsimultaneously support said housing and serve as fluid conduit.

